This clinical research effort proposes to identify and prevent acute pregnancy-induced hypertension (PIH), pre-eclampsia, in a population of socio-economically deprived nulliparous patients. Phase 1 of the study entails identification of "risk" patients by their vasoactive response to infused angiotensin II (A-II) during gestational age 27-32 weeks. Plasma renin activity, aldosterone secretion and plasma volume will be measured in 20 selected patients (10 with enhanced and 10 with blunted vasoreactivity). Phase II will be initiated thereafter in a second obstetrical population of 10 "risk" patients. Oral propranolol, a beta-adrenergic receptor antagonist, 1mg/kg body weight daily, will be used to blunt the enhanced vasopressor response to A-II during weeks 32-38. Hypothetically, the anti-renin effects of propranolol as well as the alterations in maternal cardiodynamics should prevent the development of PIH in the "risk" patient.